Compilare: user.cpp: In function ‘int main()’: user.cpp:51:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = s.size() - n + 1; i < s.size(); i++) ^ user.cpp:99:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ^